Outer loop transmit power control using channel-adaptive processing

ABSTRACT

The present invention is a system and method which controls outer loop transmit power for transmission power of an uplink/downlink communication in a wireless communication system. The system receives a communication from a base station and determines an error rate on the received communication. The system then distinguishes between static and dynamic channels, produces a static adjustment value, and characterizes the dynamic channels to generate a dynamic adjustment value. The target power level is then adjusted by the static and dynamic adjustment values, setting the transmission power level.

CROSS REFERENCE TO RELATED APPLICATIONS

The application is a continuation of Ser. No. 10/036,118 filed on Dec.26, 2001 now U.S. Pat. No. 6,622,024 which claims priority fromProvisional Patent Application No. 60/323,541, filed Sep. 20, 2001.

BACKGROUND

The present invention relates to spread spectrum time division duplex(TDD) communication systems. More particularly, the present inventionrelates to a system and method for controlling outer loop transmissionpower within TDD communication systems.

Spread spectrum TDD systems carry multiple communications over the samespectrum. The multiple signals are distinguished by their respectivechip code sequences (codes). Referring to FIG. 1, TDD systems userepeating frames 34 divided into a number of time slots 37 ₁–37 _(n,),such as fifteen time slots. In such systems, a communication is sent ina selected time slot out of the plurality of time slots 37 ₁–37 _(n)using selected codes. Accordingly, one frame 34 is capable of carryingmultiple communications distinguished by both time slot and code. Thecombination of a single code in a single time slot is referred to as aphysical channel. Based on the bandwidth required to support acommunication, one or multiple physical channels are assigned to thatcommunication.

Most TDD systems adaptively control transmission power levels. In a TDDsystem, many communications may share the same time slot and spectrum.While user equipment (UE) 22 is receiving a downlink transmission from abase station, all the other communications using the same time slot andspectrum cause interference to the specific communication. Increasingthe transmission power level of one communication degrades the signalquality of all other communications within that time slot and spectrum.However, reducing the transmission power level too far results inundesirable signal to noise ratios (SNRs) and bit error rates (BERs) atthe receivers. To maintain both the signal quality of communications andlow transmission power levels, transmission power control is used.

The purpose of power control is to use the minimum power required toallow each transport channel (TrCH) to operate with the Block Error Rate(BLER) no higher than its required level. The standard approach to TDDdownlink power control is a combination of inner and outer loop control.In this standard solution, the UE transmits physical layer transmitpower control (TPC) commands to adjust the base station transmissionpower.

A base station sends a transmission to a particular UE. Upon receipt,the UE measures the signal interference ratio (SIR) in all time slotsand compares this measured value to a targetSIR. This target SIR isgenerated from the BLER signaled from the base station. As a result of acomparison between the measured SIR value with the target SIR the UEtransmits a TPC command to the base station. The standard approachprovides for a TPC command per coded composite transport channel(CCTrCH). The CCTrCH is a physical channel which comprises the combinedunits of data for transmission over the radio interface to and from theUE or base station. This TPC command indicates to the base station toadjust the transmission power level of the downlink communication. Thebase station, which is set at an initial transmission power level,receives the TPC command and adjusts the transmit power level in alltime slots associated with the CCTrCH in unison. The inner loop powercontrol algorithm controls transmit power to maintain the received SIRas close as possible to a target SIR by monitoring the SIR measurementsof the data. The outer loop power control algorithm controls the targetSIR to maintain the received quality BLER as close as possible to atarget quality BLER based on the Cyclic Redundancy Code (CRC) check ofthe data. The output from the outer loop power control is a new targetSIR per CCTrCH used for the inner loop power control.

There are four main error sources in transmission power control: 1)channel error; 2) systematic error; 3) random measurement error; and 4)coded composite transport channel (CCTrCH) processing error. Thesystematic error and the random measurement error are correctedreasonably by the inner loop power control by monitoring the SIRmeasurements. The CCTrCH processing error is corrected by either theouter loop power control or the inner loop power control by usingrelative SIR measurements among the codes. The channel error is relatedto unknown time-varying channel conditions.

In power control systems, the outer loop power control algorithm wouldset a target SIR for each CCTrCH based on the required target BLER,assuming a most plausible channel condition. Therefore, the mismatchbetween the target BLER and the mapped target SIR varies depending onthe actual channel condition, and it is especially large at very lowBLER. Since the outer loop power control depends on the CRC check, itoften takes a long time to converge to the required target SIR for thelow BLER.

Accordingly, there is a need for outer loop power control whichdetermines the actual channel conditions so that a proper value for thetarget SIRs is used.

SUMMARY

The present invention is a system and method which controls outer looptransmit power for transmission power of an uplink/downlinkcommunication in a wireless communication system. The system receives acommunication from a base station and determines an error rate on thereceived communication. The system then distinguishes between static anddynamic channels, produces a static adjustment value, and characterizesthe dynamic channels to generate a dynamic adjustment value. The targetpower level is then adjusted by the static and dynamic adjustmentvalues, setting the transmission power level.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates time slots in repeating frames of a TDD system.

FIG. 2 illustrates a simplified wireless TDD system.

FIGS. 3A and 3B illustrate block diagrams of a UE and base station,respectively.

FIG. 4 is a graphical illustration of the mapping of the BLER with atarget SIR value.

FIG. 5 is an illustration of the jump algorithm in accordance with thepresent invention.

FIGS. 6A and 6B are block diagrams of the split sliding windows for thefirst and second filter processes.

FIG. 7 is a flow diagram of channel discrimination filtering for use indownlink power control.

FIG. 8 is a flow diagram of fading channel filtering for use in downlinkpower control.

FIG. 9 is a flow diagram of a channel-adaptive downlink outer-loop powercontrol algorithm of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The preferred embodiments will be described with reference to thedrawing figures where like numerals represent like elements throughout.

FIG. 2 illustrates a simplified wireless spread spectrum code divisionmultiple access (CDMA) or time division duplex (TDD) communicationsystem 18. The system 18 comprises a plurality of node Bs 26, 32, 34, aplurality of radio network controllers (RNC), 36, 38, 40, a plurality ofuser equipments (UEs) 20, 22, 24 and a core network 46. The plurality ofnode Bs 26, 32, 34 are connected to a plurality RNCs 36, 38, 40, whichare, in turn, connected to the core network 46. Each Node B, such asNode B 26, communicates with its associated UEs 20–24. The Node B 26 hasa single site controller (SC) associated with either a single basestation 30 ₁, or multiple base stations 30 ₁ . . . 30 _(n).

Although the present invention is intended to work with one or more UEs,Node Bs and RNCs, for simplicity of explanation, reference will be madehereinafter to the operation of a single UE in conjunction with itsassociated Node B and RNC.

Referring to FIG. 3A, the UE 22 comprises an antenna 78, an isolator orswitch 66, a modulator 64, a demodulator 68, a channel estimation device70, data estimation device 72, a transmit power calculation device 76,an interference measurement device 74, an error detection device 112, aprocessor 111, a target adjustment generator 114, a reference channeldata generator 56, a data generator 50, and two spreading and trainingsequence insertion devices 52, 58.

The UE 22 receives various radio frequency (RF) signals includingcommunications from the base station 30 ₁ over the wireless radiochannel using an antenna 78, or alternatively an antenna array. Thereceived signals are passed through a T/R switch 66 to a demodulator 68to produce a baseband signal. The baseband signal is processed, such asby a channel estimation device 70 and a data estimation device 72, inthe time slots and with the appropriate codes assigned to the UE's 22communication. The channel estimation device 70 commonly uses thetraining sequence component in the baseband signal to provide channelinformation, such as channel impulse responses. The channel informationis used by the data estimation device 72, the interference measurementdevice 74 and the transmit power calculation device 76. The dataestimation device 72 recovers data from the channel by estimating softsymbols using the channel information.

Prior to transmission of the communication from the base station 30 ₁,the data signal of the communication is error encoded using an errordetection/correction encoder 110. The error encoding scheme is typicallya CRC followed by a forward error correction encoding, although othertypes of error encoding schemes may be used. As those skilled in the artknow, the data is typically interleaved over all of the time slots andall codes.

In accordance with the preferred embodiment of the present invention,downlink outer loop power control is conducted using a channel adaptivedownlink outer loop power control, described hereafter. Using the softsymbols produced by the data estimation device 72, the error detectiondevice 112 detects the target BLER sent from the base station 30 ₁.Given the target BLER, an initial target SIR_(Target) is generated bymapping the target BLER, using an assumed plausible channel condition,to a SIR value associated with the channel condition. A graphicalexample of this mapping is illustrated in FIG. 4. The lines on thisgraph are exemplary propagation conditions, wherein the AWGN channel isthe static channel for additive white Gaussian noise, and case 1 throughcase 4 are fading channels with different multipaths.

As shown in FIG. 4, at a required BLER, for example 0.01 for a case 1fading channel, a predetermined transmission power can be determined. Inthe above example, the transmission power is approximately 4.5 dB, fromwhich a target SIR is calculated. It is also shown in FIG. 4 that theSIR_(Target) at BLER of 0.01 for the case 1 fading channel requires morethan 5 dB over the SIR_(Target) for the case 2 fading channel.Accordingly, it will take longer to converge to the requiredSIR_(Target) for a low BLER when assuming the case 1 fading channel andtrying to get to the SIR_(Target) for a case 2 fading channel.

In order to get from the SIR for the case 1 channel, the assumedchannel, for example, to the required SIR for the case 2 channel, theactual channel for example, a jump algorithm is utilized by theprocessor 111. Initially, the parameters of the jump algorithmSIR_step_down, SIR_step_up are determined using the target BLER inaccordance with the following equations:SIR_step_down=SIR_step_size*target_(—) BLER  Equation 1SIR_step_up=SIR_step_size−SIR_step_down;  Equation 2where SIR_step_size is any predetermined value, preferably a valuebetween 0.3 dB and 0.5 dB. As the error detection device 112 detects anerror in a Transmission Time Interval (TTI), a SIR_(Target) value isupdated by the processor 111 in accordance with Equation 3:SIR _(Target)(K)=SIR _(Target)(K−1)+SIR_step_up(dB)  Equation 3where K is the number of the TTI. If the error detection device 112 doesnot detect an error in the TTI, the SIR_(Target) is updated inaccordance with Equation 4:SIR _(Target)(K)=SIR _(Target)(K−1)−SIR_step_down(dB)  Equation 4

Also, each time a determination is made by the error detector device 112whether an error is present in a TTI, a step_up counter or step_downcounter is incremented; the step_up counter being incremented each timean error is detected; the step_down counter being incremented otherwise.A graphical representation of the jump algorithm used by the processor111 to set a target SIR is illustrated in FIG. 5. Again, FIG. 5illustrates that for communications where the assumed channel conditiondiffers greatly from the actual channel condition, the convergence froman assumed target SIR to an actual SIR may take a long time.

Accordingly, the processor 111 then conducts a channel-adaptivefiltering process to further adjust the SIR_(Target). The channeladaptive filtering process includes two (2) filter processes. The firstfilter process distinguishes the static and dynamic (or fading)channels, and the second filter process characterizes the dynamicchannel conditions. These filter processes are conducted sequentially,(i.e. the second after the first), with one another to produce thenecessary adjustments to the SIR_(Target) in accordance with actualchannel conditions.

Both of the filter processes perform their respective filter processingusing a split sliding window 600, 610. Diagrams of the split slidingwindows 600, 610 are shown in FIGS. 6A and 6B, respectively. The splitsliding windows 600, 610 comprise a left side window (LW), a variablegap (GW) and a right side window (RW). Each of the respective windowsmay be any length in size; the length representing the number of values,observations O₁, O₂, to be determined for each of respective windows LW,RW. GW represents a transition period of channel conditions, whichimproves the detection of changing channel conditions. For example, ifthe left side window LW was set to a length of 2, the LW would comprisetwo observations of the respective sliding windows 600, 610.

Each of the respective sliding windows 600, 610 observations' O₁, O₂ aregenerated each observation period OP₁, OP₂ being any number of timesegments within the received communication. For example, the firstfilter process sliding window 600 may have an observation period OP₁ of100 ms, where one (1) time segment equals 10 ms. Accordingly, oneobservation O₁ is made every ten (10) time segments. This is the casefor the second filter process sliding window 610 as well. It should benoted, though, that the observation periods OP₁, OP₂ of the filterprocesses may be different. The sliding window moves one step forwardper observation period OP₁, OP₂ and the each of the filtering processesdiscriminates channel conditions between RW and LW. The valuesobserved/measured O₁, O₂ within RW and LW are utilized by the filteringprocesses to generate a SIR adjustment value.

The algorithm characterizes the channel condition based on the power ofthe strongest path (P₀) for static/dynamic channel detection in thefirst filter process and the power ratio of P₁/P₀ (dB) for fadingchannels, where P₁ is the power of the second strongest path. P₀ issampled once per observation period OP₁ for the first filter process andP1/P₀ (dB), for the second filter process, are averaged once perobservation period OP₂ for the second filter process. Each observationO₁, O₂ is stored in the memory to perform filtering by the split slidingwindows 600, 610.

As stated, the first filtering process 700 distinguishes the static(i.e., path of line of sight) and dynamic channels (i.e. fadingmultipath), determining whether there is a transition between a dynamicchannel and a static channel. FIG. 7 is a flow diagram of the firstfiltering process 700 in accordance with the preferred embodiment of thepresent invention. The distinguishing of the static and dynamic channelsis conducted using the detected peak power of a predeterminedobservation period OP₁.

As explained above, the first filtering process utilizes the splitsliding window, as shown in FIG. 6A, to generate a static adjustmentvalue. Again, the LW and RW can be of any predetermined length. The GWinitially is set to one (1) (Step 702) and is increased by one (1) eachiteration, to be disclosed hereinafter. The GW, though, has a presetlimitation as to how big it can be, for example, 2 or 3.

The processor 111 utilizes the step_up and step_down counts generated inthe aforementioned jump algorithm, as well as, the determined power(s)of the strongest path in the LW and RW to calculate the staticadjustment value. The first filter process is run after the LW and theRW are filled in with observed/measured peak powers. Accordingly, if thesliding window size was 7, (RW equal 3, LW equals 3 and GW equals 1), 7observations O₁ would have to be observed before the first filterprocess generates a static adjustment value.

The static adjustment value is calculated in accordance with thefollowing. The mean of the peak values of each observation in the LW andRW and the Δ mean of the peak values are calculated (Step 703) inaccordance with Equations 5, 6 and 7 below: $\begin{matrix}{{mean\_ peak}_{RW} = {\frac{1}{RW}{\sum\limits_{i = 1}^{RW}{P_{0}(i)}}}} & {{Equation}\mspace{20mu} 5} \\{{mean\_ peak}_{LW} = {\frac{1}{LW}{\sum\limits_{i = {{RW} + {GW} + 1}}^{N}{P_{0}(i)}}}} & {{Equation}\mspace{20mu} 6} \\{{\Delta\;{mean\_ peak}} = {{mean\_ peak}_{RW} - {mean\_ peak}_{LW}}} & {{Equation}\mspace{20mu} 7}\end{matrix}$

Once the Δ mean peak value has been calculated, a threshold test isconducted (Step 704) to determine whether there is a fluctuation amongpeak powers within each window (LW and RW) and whether there is a changebetween the RW and LW windows, meaning a change from static to dynamicor dynamic to static channels within the sliding window. The thresholdvalue is a predetermined value, preferably:TH _(mean) _(—) _(peak)=3.0TH_Peak_(std,RW)=1.0TH_Peak_(std,LW)=1.0Th_Peak_(std,RW) and TH_Peak_(std,LW) are thresholds which are relatedto the standard deviation (std) to detect a fluctuation of peak powersfor fading channels. The threshold test compares the Δ mean peak valuesto the threshold and the peak values of the RW and LW to determine ifthere is a transition, meaning the channel within the LW is differentthan the channel within the RW, to determine if the channel within theLW is a static channel when the channel within the RW is a fadingchannel, and vice versa.

If the LW and RW channels are different and either one is static, theprocessor 111 sets the jump value SIR_(jump) based on the step_up andstep_down counts of the jump process and computes the initial value ofthe target SIR static adjustment (adjStaticSIRdB) based on the deltamean and BLER (Step 705).

The jump value is set according to Equation 8a.SIR _(jump)=SIR_step_up*step_up_count−SIR_step_down*step_down_count  Equation 8aThe initial value of adjStaticSIRdB, which is an adjustment valuerelative to an assumed reference dynamic channel, (preferably case 2),is set according to Equation 8b; where the BLER is mapped using thegraphs shown FIG. 4.adjStaticSIRdB=−1.5*Δmean peak*log 10(1.0/BLER)  Equation 8b

The initial value of adjStaticSIRdB is then modified based on the powerratio, depending on whether the RW channel is static or the LW channelthat is static. If the RW channel is the static channel (and the LWchannel is the fading channel), the adjStaticSIRdB is modified with theaverage power ratio of the LW (AvPrevChChar) according to the pseudocode and Equation 9 set forth below:

AvPrevChChar = 0; Equation 9 forj = 1:sizeofLW AvPrevChChar =AvPrevChChar + prevChChar(1,j + sizeofRW + maxsizeofGap − 1); endAvPrevChChar = AvPrevChChar / sizeofLW; deltaMean = AvPrevChChar + 10.8;adjStaticSIRdB = adjStaticSIRdB + 0.4 * deltaMean * log10(1.0 / BLER).If the LW channel is the static channel (and the RW channel is thefading channel), the adjusted static SIR adjStaticSIRdB is calculatedaccording to Equation 10:adjStaticSIRdB=adjStaticSIRdB−0.4*delta mean*log 10(1.0/BLER)  Equation10where delta mean=7.0.

Once the initial static adjustment is re-calculated, a determination ismade as to whether the adjustment is too large, which protects againstmaking large adjustments at one time. This is accomplished by comparingthe static adjustment to a maximum adjustment maxadjSIRdB, wheremax adjSIRdB=3*log 10(1/BLER).  Equation 11If the maximum is less than the calculated adjustment, the maximum valueis utilized as the static adjustment. The processor 111 then adjusts thestatic adjustment in accordance with Equation 12:adjStaticSIRdB=adjStaticSIRdB−SIRjump  Equation 12

Upon the calculation of the static adjustment, the processor 111initializes the peak power, step_up and step_down counts, and powerratio for the new channel (Step 706). The initialization of the powerratio will set the reference channel to the case 2 assumed referencechannel used in Equation 8b, to begin the second filter process. Theinitialization of the step_up and step_down counts will set Equation 8ato zero in the second filter process so that the SIR_(jump) adjustmentis not used twice.

If the threshold test is not passed (i.e., a change between the RW andLW windows is not detected) and the gap size is less than the maximumgap size, the processor 111 increases the gap size by one (1) (Step 708)and the peak values of the LW and RW and Δ mean are recalculated (Step703). If the GW is at the predetermined maximum, the processor 111 movesthe sliding window and begins the next observation period OP₁ (Step707).

As stated above, the processor 111 sequentially conducts the secondfilter process 800 to generate a dynamic (fading) channel adjustment.The second filter process 800 characterizes fading channel conditions byusing a power ratio of multipaths. The flow diagram of the secondfiltering process 800 is illustrated in FIG. 8. When the first filterprocess 700 is initially run, the values in the LW and RW of the firstfilter are accumulated by the observed/measured peak powers, while thevalues in the LW of the second filter process 800 are predetermined bythe power ratios of the assumed plausible channel condition, for examplecase 1, and the values in the GW and RW of the second filter process 800are accumulated by the observed/measured power ratios. Once the RW hasaccumulated an observations O₂ worth of data, the power ratio withinthat observation O₂ is determined. Those predetermined power ratiovalues within the LW and any second or third observed/measured valuewithin RW are used by the processor 111 to determine the adjustmentvalue.

Similar to the first filter process 700, the second filter process 800computes the mean difference of the LW and RW power ratio valuescomputed in each. As stated earlier, the sliding window for the secondfilter process 800 comprises a LW, RW and GW, which can be of anypredetermined length (Step 803). The power ratio for each observation ineach window is computed according to Equation 13 below: $\begin{matrix}{{P_{10}(i)} = {\frac{1}{N_{obs}}{\sum\limits^{N_{obs}}{10*\left\lbrack {{\log\left( {P_{1}(j)} \right)} - {\log\; 10\left( {p_{0}(j)} \right)}} \right\rbrack}}}} & {{Equation}\mspace{14mu} 13}\end{matrix}$where N_(obs) is the number of samples per observation period OP₂, P₀(j)is the power of the strongest path and P₁(j) is the power of the secondstrongest path.

The mean power ratios and the delta mean (Δmean) are then calculated inaccordance with equations 14, 15 and 16 below: $\begin{matrix}{{mean}_{RW} = {\frac{1}{RW}{\sum\limits_{i = 1}^{RW}{P_{10}(i)}}}} & {{Equation}\mspace{14mu} 14} \\{{mean}_{LW} = {\frac{1}{LW}{\sum\limits_{i = {{RW} + {GW} + 1}}^{N}{P_{10}(i)}}}} & {{Equation}\mspace{14mu} 15} \\{{\Delta\;{mean}} = {{mean}_{RW} - {mean}_{LW}}} & {{Equation}\mspace{14mu} 16}\end{matrix}$

Similar to the first filter process 700, threshold values are generatedand the mean and power ratios of the RW and LW are compared to thethreshold (Step 804). The threshold values are computed in accordancewith the following pseudo-code:

if((mean_(LW) > −7.0)&(mean_(RW) > −7.0)) TH_(mean) = 2.0; TH_(std,LW) =abs(0.35 * Δmean); TH_(std,RW) = abs(0.5 * Δmean); else TH_(mean) = 3.0;TH_(std,LW) = abs(0.3 * Δmean); TH_(std,RW) = abs(0.5 * 0.3 * Δmean);Endwhere −7.0 represents the fading channel conditions that have weaksecond path or no second path.

If the mean difference and the power ratio values of the RW and LW arewithin the threshold range, the processor 111 sets the SIR_(jump) and aninitial fading channel SIR adjustment (Step 805) according to Equations17 and 18, below:SIR _(jump)=SIR_step_up*step_up_count−SIR_step_down*step_down_count  Equation 17SIR _(target) ^(adj) =a*Δmean*log 10(1/BLER)  Equation 18where the BLER is again mapped from the assumed reference channel.

If the initial SIR_(target) ^(adj) is greater than a maximum adjustment,max adjSIRdB=3*log 10(1/BLER)  Equation 19then the SIR_(target) ^(adj) is set to maxadjSIRdB. The processor 111then adjusts the initial or maximum adjustment SIR_(target) ^(adj) bySIR_(jump):SIR _(target) ^(adj) =SIR _(target) ^(adj) −SIR _(jump)  Equation 20The SIR_(target) ^(adj) presents a fading channel adjustment to theassumed reference channel. For example, if the assumed reference channelis case 2 and the actual channel condition is a case 3 channel, theSIR_(target) ^(adj) adjusts the static adjustment generated by the firstfilter process 700 to reduce or increase the static adjustment value sothat the target SIR sent to the base station represents actual channelconditions of the case 3 channel.

If the threshold test is not passed, the second filter process operatessimilar to the first filter process in that the gap size is incrementedby one (1) (Step 808) if it is not greater than or equal to the maximumgap size, or the sliding window moves by one step forward for the nextobservation period (Step 807) and the SIR_(target) ^(adj) is set to 0.

Each time an observation is completed for the first and/or second filterprocess, the SIR_(Target) is determined according to Equation 21, below:target_(—) SIR(k)=target_(—) SIR(k−1)+adjstaticSIRdB+SIR _(target)^(adj)  Equation 21

The processor 111 determines the adjustment of the base station transmitpower by comparing the measured SIR with the SIR_(Target). Using thiscomparison, a TPC command is subsequently sent to the base station 80.

Referring to FIG. 3B, the base station 80 comprises, an antenna 82, anisolator or switch 84, a demodulator 86, a channel estimation device 88,a data estimation device 90, processor 103, a transmission powercalculation device 98, a data generator 102, an encoder 110, aninsertion device 104 and a modulator 106. The antenna 82 or,alternately, antenna array of the base station 30 ₁ receives various RFsignals including the TPC command. The received signals are passed via aswitch 84 to a demodulator 86 to produce a baseband signal.Alternatively separate antennas may be used for transmit or receivefunctions. The baseband signal is processed, such as by a channelestimation device 88 and a data estimation device 90, in the time slotsand with the appropriate codes assigned to the communication burst ofthe UE 22. The channel estimation device 88 uses the training sequencecomponent in the baseband signal to provide channel information, such aschannel impulse responses. The channel information is used by the dataestimation device 90. The data information is provided to the transmitpower calculation device 98 by processor 103.

Processor 103 converts the soft symbols produced by the data estimationdevice 90 to bits and extracts the TPC command associated with theCCTrCH. The transmit power calculation device 98 increases or decreasesthe transmission power for the CCTrCH by the predetermined step sizeaccording to the TPC command.

Data to be transmitted from the base station 30 ₁ is produced by datagenerator 102. The data is error detection/correction encoded by errordetection/correction encoder 110. The error encoded data is spread andtime-multiplexed with a training sequence by the training sequenceinsertion device 104 in the appropriate time slot(s) and code(s) of theassigned physical channels, producing a communication burst(s). Thespread signal is amplified by an amplifier 106 and modulated bymodulator 108 to radio frequency. The gain of the amplifier iscontrolled by the transmit power calculation device 98 to achieve thedetermined transmission power level for each time slot. The powercontrolled communication burst(s) is passed through the isolator 84 andradiated by the antenna 82.

The flow diagram of the channel-adaptive downlink outer-loop powercontrol algorithm of the present invention is illustrated in FIG. 9. Atarget BLER is communicated to the receiver 10 from the base station 30,(Step 901). Using the received target BLER, a target SIR is obtained fora given channel (Step 902) and the step_up and step_down sizes for thejump algorithm are calculated (Step 903). The step_up and step_downcounters are initialized and the parameters for the first and secondfilter processes are set (i.e., observation periods) (Step 904).

If the receiver 10 is synchronized with the base station and there is nodiscontinuation of transmission (DTX), the jump algorithm is conductedby the processor 111 (Step 905). Upon the generation of the SIR_(Target)by the jump algorithm, the processor 111 conducts the first filterprocess (Step 906) to generate a static adjustment value. Once the firstfilter process has accumulated enough observations to fill the firstsliding window, the process calculates the peak power (Step 907) andgenerates the static SIR adjustment (Step 908). The processor 111 thenconducts the second filter process (step 909). The power ratios arecalculated for each observation O₂ within the second filter window (step910) and generates the fading channel adjustment (Step 911). TheSIR_(Target) is then adjusted according to the adjustment valuesgenerated by the first and second filter processes respectively 700, 800(Step 912).

The downlink outer loop power control algorithm, in accordance with thepreferred embodiment of the present invention utilizes a jump algorithmand a channel-adaptive algorithm to mitigate the channel error andadapts to the time-varying channel conditions. If the channel-adaptivealgorithm uses more samples of P0 and P1/P0 per frame or uses PCCPCH ofSCH prior to the TPC, it could shorten the convergence time. Hence thechannel-adaptive outer-loop power control algorithm will meet thedesirable convergence time and reduce the battery power consumption inthe uplink TPC and interference in the downlink TPC (results in morecapacity). The channel-adaptive algorithm can be extended by adding morefeatures, P2/P0, P3/P0, the number of multi-paths, etc. to improveperformance. Since the algorithm is general, it can be applied to theuplink TPC of TDD and the uplink/downlink TPC of FDD.

While the present invention has been described in terms of the preferredembodiment, other variations which are within the scope of the inventionas outlined in the claims below will be apparent to those skilled in theart.

1. A method for controlling outer loop transmit power for transmissionpower control of an uplink/downlink communication in a wirelesscommunication system where a user equipment (UE) produces a target powerlevel based upon received signals which it communicates to a basestation from which the signals are received, the method comprising thesteps of: receiving at the UE a communication in the form of a series ofcommunication segments from a base station; analyzing the receivedcommunication within first and second composite windows; periodicallydistinguishing between static and dynamic channel conditions incommunication segments within the first and second windows; generating astatic adjustment value when the respective channel conditions of thecommunication segments in said first and second windows are different;and adjusting the target power level in response to the staticadjustment value.
 2. The method of claim 1 wherein: said first compositewindow has a predefined first window of a first length of apredetermined number of communication segments and a non-overlappingsecond window of a second length of a predetermined number ofcommunication segments, such that each segment of the communication isfirst analyzed in the first window and subsequently analyzed in thesecond window; and said second composite window has a predefined thirdwindow of a third length of a predetermined number of communicationsegments and a non-overlapping fourth window of a fourth length of apredetermined number of communication segments, such that each segmentof the communication is first analyzed in the third window andsubsequently analyzed in the fourth window.
 3. The method of claim 2further comprising: periodically characterizing dynamic channelconditions in communication segments within the third and fourth windowsto generate a dynamic adjustment value; and adjusting the target powerlevel in response to the static adjustment value.
 4. The method of claim3 further comprising the steps of: receiving from the base station adetected target power level; detecting an error signal; and adjustingthe detected target power level in response to said detection of theerror signal to generate the target power level before adjusting thetarget power level in response to the static and dynamic adjustmentvalues.
 5. The method of claim 3 wherein: said distinguishing stepincludes the steps of: detecting a peak power point of saidcommunication segments each observation O1 for said first and secondwindows, respectively; comparing said detected peak power points to apredefined threshold value; determining which of the first and secondwindows includes static channel conditions based upon said comparison;and calculating said static adjustment value in response to saiddetermination; and said characterizing step includes the steps of:detecting peak power ratios of said communication segments eachobservation O2 for the third and fourth windows, respectively; comparingsaid detected power ratios to a second threshold value, said secondthreshold value being based in part on said peak power ratios; andgenerating the dynamic adjustment value when the comparison is withinthe threshold.
 6. The method of claim 5 wherein: said first window andsaid second window are separated by a first transition window of a fifthlength and said first transition window is adjusted when said detectedpeak power points are not within the threshold value; and said third andfourth windows are separated by a second transition window of a sixthlength, and said second transition window is adjusted when said detectedpower ratios are not within said second threshold.
 7. The method ofclaim 2 wherein said third and fourth windows include a respectivepredetermined number of observations O2, said observation O2 being equalto a fixed number of communication segments and representing a timeperiod OP2, and said periodic characterizing of the dynamic channelconditions is based upon values determined from each observation O2. 8.The method of claim 9 wherein said characterizing step comprises thesteps of: detecting peak power ratios of said communication segmentseach observation O2 for the third and fourth windows, respectively;comparing said detected power ratios to a second threshold value, saidsecond threshold value being based in part on said peak power ratios;and generating the dynamic adjustment value when the comparison iswithin the threshold.
 9. The method of claim 8 wherein said third andfourth windows are separated by a second transition window of a sixthlength, and said second transition window is adjusted when said detectedpower ratios are not within said second threshold.
 10. The method ofclaim 9 wherein the period of said characterizing is OP2.
 11. The methodof claim 1 wherein said first and second windows include a respectivepredetermined number of observations O1, each said observation O1 equalto a fixed number of communication segments and representing a timeperiod OP1; and said periodic distinguishing between static and dynamicchannel conditions is based upon values determined from each observationO1.
 12. The method of claim 11 wherein said distinguishing step includesthe steps of: detecting a peak power point of said communicationsegments each observation O1 for said first and second windows,respectively; comparing said detected peak power points to a predefinedthreshold value; determining which of the first and second windowsincludes static channel conditions based upon said comparison; andcalculating said static adjustment value in response to saiddetermination.
 13. The method of claim 12 wherein said first window andsaid second window are separated by a first transition window of a fifthlength and said first transition window is adjusted when said detectedpeak power points are not within the threshold value.
 14. The method ofclaim 11 wherein said period of said distinguishing is equal to P1. 15.The method of claim 1 wherein said first and second windows include arespective predetermined number of observations O1, each saidobservation O1 equal to a fixed number of communication segments andrepresenting a time period OP1; and said periodic distinguishing betweenstatic and dynamic channel conditions is based upon values determinedfrom each observation O1; said third and fourth windows include arespective predetermined number of observations O2, said observation O2being equal to a fixed number of communication segments and representinga time period OP2, and said periodic characterizing of the dynamicchannel conditions is based upon values determined from each observationO2.
 16. The method of claim 15 wherein said period of saiddistinguishing is equal to P1, and the period of said characterizing isOP2.
 17. The method of claim 16 wherein said observations O1 and O2 arenot equal.
 18. A receiver in a wireless communication system where auser equipment (UE) produces a target power level based upon receivedsignals which it communicates to a base station from which the signalsare received, which controls outer loop transmit power for transmissionpower control of an uplink/downlink communication and receives acommunication in the form of a series of communication segments from abase station, comprising: an error detection device for determiningwhether an error is present in a transmission time interval (TTI); and aprocessor in communication with the error detection device, theprocessor for generating the target power level which is communicated tosaid base station and analyzing the received communication within firstand second composite windows.
 19. The receiver of claim 18, wherein:said first composite window has a predefined first window of a firstlength of a predetermined number of communication segments and anon-overlapping second window of a second length of a predeterminednumber of communication segments, such that each segment of thecommunication is first analyzed in the first window and subsequentlyanalyzed in the second window, for periodically distinguishing betweenstatic and dynamic channel conditions in communication segments withinthe first and second windows and generating a static adjustment valuewhen the respective channel conditions of the communication segments insaid first and second windows are different; said second compositewindow has a predefined third window of a third length of apredetermined number of communication segments and a non-overlappingfourth window of a fourth length of a predetermined number ofcommunication segments, such that each segment of the communication isfirst analyzed in the third window and subsequently analyzed in thefourth window, for periodically characterizing dynamic channelconditions in communication segments within the third and fourth windowsto generate a dynamic adjustment value; and said processor adjusts thetarget power level in response to the static and dynamic adjustmentvalues.
 20. The receiver of claim 19 wherein: said receivedcommunication includes a detected target power level; said processorfurther receives an error signal from said error detection device; andthe detected target power level is adjusted in response to saiddetection of the error signal to generate the target power level beforeadjusting the target power level in response to the static and dynamicadjustment values.
 21. The receiver of claim 19 wherein said first andsecond windows include a respective predetermined number of observationsO1, each said observation O1 equal to a fixed number of communicationsegments and representing a time period OP1; and said periodicdistinguishing between static and dynamic channel conditions is basedupon values determined from each observation O1.
 22. The receiver ofclaim 19 wherein said first window and said second window are separatedby a first transition window of a fifth length and said first transitionwindow is adjusted when the first and second windows are not different.23. The receiver of claim 19 wherein said period of said distinguishingis equal to P1.
 24. The receiver of claim 19 wherein said third andfourth windows include a respective predetermined number of observationsO2, said observation O2 being equal to a fixed number of communicationsegments and representing a time period OP2, and said periodiccharacterizing of the dynamic channel conditions is based upon valuesdetermined from each observation O2.
 25. The receiver of claim 19wherein said third and fourth windows are separated by a secondtransition window of a sixth length.
 26. The method of claim 24 whereinthe period of said characterizing is OP2.
 27. The receiver of claim 19wherein said first and second windows include a respective predeterminednumber of observations O1, each said observation O1 equal to a fixednumber of communication segments and representing a time period OP1; andsaid periodic distinguishing between static and dynamic channelconditions is based upon values determined from each observation O1;said third and fourth windows include a respective predetermined numberof observations O2 said observation O2 being equal to a fixed number ofcommunication segments and representing a time period OP2 , and saidperiodic characterizing of the dynamic channel conditions is based uponvalues determined from each observation O2.
 28. The receiver of claim 27wherein said period of said distinguishing is equal to P1, and theperiod of said characterizing is P2.
 29. The receiver of claim 28wherein said observations O1 and O2 are not equal.